Unstained Clonorchis sinensis egg in feces showing the shoulder at the rim of the operculum. (Tropical Medicine Resource Center

The Clonorchis sinensis egg is a small operculated egg which ranges from 27 to 35 µm in length by 11 to 20 µm in width.  They are oval in shape and have a broad posterior end and a convex operculum located at the smaller end of the egg resting on “shoulders.”  At the opposite (larger, abopercular) end, a small knob or hook-like protrusion is often visible.  The miracidium is visible inside the egg.  They are yellow brown in color, and the thick shell may be covered by adhering debris. For more images click here.


(Adult Clonorchis sinensis, acetocarmine stained. Its uterus is full of eggs, ovary and two tandem branched testes are seen well. Courtesy of Sung-Tae Hong

As an adult, C. sinensis is a very narrow fluke, 10-25 mm. in length, flattened dorsal-ventrally, with Trematode characteristics such as an oral/anterior sucker, a ventral sucker (also known as the acetabulum), no blood circulatory system, and no body cavity. The common genital pore is just anterior to the acetabulum. The fluke is tapered at the anterior end and rounded at the posterior end. (University of Michigan Animal Diversity Web) For more images click here.






(Egg of Clonorchis sinensis. 30 um x 16 um. Courtesy of Sung-Tae Hong

(Clonorchis eggs in tissue sample. Tropical Medicine Resource Center



(Adult in liver. Tropical Medicine Resource Center


Home    History of Discovery    Epidemiology    Life Cycle    Clinical Presentation    Diagnosis    Enterotest    Images    Treatment    Public Health and Prevention    References    Web Links